Air bleed adjusting device for the carburetor of an internal combustion engine

ABSTRACT

The amount of bled air adjusting device for the carburetor of an internal combustion engine having a valve assembly settled between an air path to the air bleeding holes on a nozzle of the carburetor and the atmosphere, which has two ports in parallel with each other, just one of them has a cutoff valve to permit air to pass therethrough from the atmosphere to said air path at a temperature of the engine above a predetermined temperature during warming-up running of the engine, and the other has a variable orifice valve to permit air to pass therethrough from the atmosphere to said air path in association with said cutoff valve of the former as the temperature of the engine rises higher than said predetermined temperature during normal running of the engine after the warming-up running.

United States Patent 1 1 Im ai Oct. 9, 1973 [54] AIR BLEED ADJUSTING DEVICE FOR THE 2,981,245 4/1961 Sarto 261/39 D CARBURETOR OF AN INTERNAL 2,986,380 5/1961 Read 3,387,830 6/1968 Mcllroy; 261/121 A COMBUSTION ENGINE [75] Inventor: Yasuhiro Imai, Y amato-machi,

\ Japan [73] Assignee: Honda Giken Kogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: Oct. 8,1971 21 Appl. No.: 187,602

[30] Foreign Application Priority Data Oct. 9, 1970 Japan 45/88263 [52] US. Cl 261/39 B, 261/121 B, 261/44 R [51] Int. Cl.... F02m 7/24 [58] Field of Search); 261/121 B, 39 B, 261/44 R, 39 D [56] References Cited UNITED STATES PATENTS 1,809,648 7 6/1931 Timian 261/39 B 1,861,725 6/1932 Stokes 261/39 D 2,245,139 6/1941 Beck 261/39 D Prirr ary Examiner-Tim R. Miles Attorney-Eric H. Waters et a1.

[57] ABSTRACT retor of an internal combustion engine having a valve assembly settled between an air path to the air bleeding holes on a nozzle of the carburetor and the atmosphere, which has two ports in parallel with each other, just one of them has a cutoff valve to permit air to pass therethrough from the atmosphere to said air path at a temperature of the engine above a predetermined temperature during warming-up running of the engine, and the other has a variable orifice valve to permit air to pass therethrough from the atmosphere to said air path in association with said cutoff valveof the former as the temperature of the engine rises higher than said predetermined temperature during normal running of the engine after the warming-up running.

2 Claims, 3 Drawing Figures PATENTED BET 9 I973 FIG. -I

TEMPEEATURE OF ENGINE 9 $52 6 i656 mi 5 6 U6 E osz AIR BLEED ADJUSTING DEVICE FOR CARBURETOR OF AN INTERNAL COMBUSTION ENGINE BRIEF SUMMARY OF THE INVENTION mixed gas used to be adjusted by controlling operation with a choke valve just during warming-up'running of the engine subsequent to starting operation thereof, but not after the warming-up runningthereof, while just predeterminedly concentrated mixed .gas used to be supplied into the interior of the intake pipe of the engine during normalrrunning of theengine subsequent to the warming-up running thereof.

In this case, if theengineisstill under high speed-run ning after warming-up running thereof, the temperature of the engine'rises, and the mixed gas in the intake pipe gets excessively concentrated because of acceleration of evaporation of the mixed gas in the intake pipe and decreasing of the efficiency of filling up of air in the intake pipe with expansion of theair.

Therefore, the purposexof the presentinvention is to provide an airbleed adjusting device for the carburetor of an internal combustion engine which supplies properly concentrated mixedgas inaccordance with variation-of the temperature-of the engine even during and after warming-up running -'of the engine, by adjusting the amount of air bledgfrom the air bleeding holes to the nozzle .of the carburetor.

According tothe present invention, an air bleed adjusting device for the carburetor of an internalcombustion'engine. has a valve assembly settled between an air path to the air bleeding holes ona'nozzle of the carburetor and the atmosphere. The valve assembly has two ports in parallel with each other. One ofthem has a cutoff valve to permit air to'pass therethrough from the atmosphere to said airpath, andthe other has a variable orifice valve to permit :air to'passtherethrough from the atmosphere to'said air path.'But the variableorifice valve is to operate after operation of thecutoff valve as the temperature of the engine rises.

BRIEF DESCRIPTION OF THE DRAWING 1 present-invention, 'with respect to the temperature of the engine.

DETAILED DESCRIPTION Referring to'FIGVI of the drawing, therein is seena carburetor l having-an intake'way 2 formedalong the center portionthereof a negative pressure chamber 3 settled on the upper outsideportion thereof,which opthe density of eration is to be affected by negative pressure in the way 2,'and a float chamber 4 settled on the. lower outside portion thereof. A piston 5 protruded inside the way 2 is moved up and down by the force of vacuum in the negative pressure chamber 3 to form a variable Venturi pipe 2' in association with the inner surface of the way 2.

' Thev piston 5 has a needle 6 elongated downwards therefrom so that the needle 6 can be inserted into the inside of a main nozzle 7 settled at the bottom portion of the variable Venturi pipe 2, and vary the cross sectional area at the outlet portion of the nozzle 7.

The inside of the main nozzle 7 is in conjunction with the float chamber 4 through a main jet pipe 8 settled at the lowermost portion of the main nozzle 7, which is usually positioned in fuel in the fuel pan of the float chamber 4. Moreover, the nozzle 7 is surrounded by an air bleeding chamber 10 which is in conjunction with the inside of the nozzle 7 through a number of air bleeding holes cut through the circumferential wall of the nozzle 7.

An air path 11 led into the chamber 10 is connected to a valve assembly V through a pipe 12.

The valve assembly V is settled on the outer surface of the intake pipe 13, which is relatively attached to the carburetor 1, of an internal combustion engine. The valve assembly V has an air chamber 15 in connection with the atmosphere through an air cleaner 14 andan air passage 16 in connection with the air path 11. Between the air chamber 15 and the air passage 16,:two ports 17, 18 are formed. The port 17 has a cutoff valve l9, while the port 18 has a variable orifice valve 20.

The cutoff valve 19 is formed with the valve body 22, which is mounted on the top portion of the bimetallic plate 21 attached to the proper portion of the inner wall of the chamber 15 at its root portion, in association with the port 17. On the other hand, the variable orifice valve 20 is formed with the needle valve 24,-

which is enforced to close the valve 20 by a spring 23, in association with the port 18.

As shown in FIG. 2, another bimetallic plate 25.is also attached to the inner wall of the chamber 15 in parallel with the bimetallic plate 21, and the'free end of the plate 25 is in contact with the top of the needle valve 24.

The plate 21 curves downwards to separate the valve body 22 from the port 17 as the temperature of the engine rises (at a temperature above about 30 C), while the other plate 25 curves upwards to push up the'needle valve 24 asthe temperature of the engine. rises (at a temperature above about C).

Inside the port 17, a throttle 26 is fitted to have proper resistance against air flow passing therethrough.

In addition, the carburetor 1 has a choke valve27, a throttle valve 28 and a sub-nozzle 29 attached a sub-jet pipe thereto. v

As for operation of the assembly described above,

' after the engine is started, the bimetallic plate 21 begins to curve downwards to open the cutoff valve. 19 at temperature of the engine as about 30 C. Then, the cutoff valve 19 is fully opened at about 40 C to pass air therethrough from'the air chamber 15 to the port 17. After that, air goes into the air bleeding chamber .10 through the air passage 16, the pipe 12 and the air path 11, and is mixed with fuel injected with the main jet pipe S'to make mixture having proper concentration for warming-up running of the engine after starting operation, and then is supplied into the intake way 2.

After the warming-up running of the engine, the other bimetallic plate 25 begins to curve upwards to push up the needle valve 24 against the force of the spring 23 and open the variable orifice valve 20 at a temperature of the engine above about 60 C. The variable orifice valve opens wider as the temperature of the enginerises, to permit air to pass through itself and the port 18 from the air chamber 15 to'the air passage 16. At this condition, so much air can pass through both the ports 17 and 18 from the air chamber 15 to the air passage 16, that the amount of bled air can be fully increased.

As shown in FIG. 3, the amount of bled air is increased-as the temperature of the engine rises so as to supplement the decreased amount of air in the intake pipe of the engine at a high temperature, while properly concentrated mixed gas is supplied in accordance with rising of the temperature of the engine.

Therefore, according to the present invention, the character of an internal combustion engine is improved by adjusting the amount of bled air with a cutoff valve during warming-up running of the engine, and with both the cutoff valve and a variable orifice valve after the warming-up running, to constantly supply properly concentrated mixed gas into the interior of the intake way of the engine.

.It is noticed that the present invention can be applied to the sub-nozzle instead of the main nozzle.

What is claimed is:

1. An air bleed adjusting device for a carburetor with nozzle of an internal combustion engine comprising, air path means to air bleeding holes on the nozzle of the carburetor; atmospheric path means open to the atmosphere; valve means between said air path means and said atmospheric path means, said valve meansv having two ports parallel to each other; engine temperature sensing means; a cut-off valve and a fixed orifice in one of said ports to permit air to pass therethrough from the atmosphere to said air path means when the engine temperature reaches the final temperature during the warming-up phase of the engine; a variable orifice valve in the other port to permit additional air to pass therethrough from the atmosphere to said air path means in proportion to increasing engine temperature over the operating temperature range, said operating temperature range being higher than the final temperature of the warming-up phase of the engine, whereby the density of the gas mixture is maintained at a substantially high level over lower temperature range compared to the final temperature of the warming-up phase, said density being held at a substantially low level over higher temperature compared to the final temperature of the warming-up phase.

2. The air bleed adjusting device as defined in claim 1 wherein the amount of bled air is relatively increased at a rapid rate upon reaching the final temperature of the warming-up phase and then increased less rapidly in proportion to increase in temperature of the engine. 1F I. I? 

1. An air bleed adjusting device for a carburetor with nozzle of an internal combustion engine comprising, air path means to air bleeding holes on the nozzle of the carburetor; atmospheric path means open to the atmosphere; valve means between said air path means and said atmospheric path means, said valve means having two ports parallel to each other; engine temperature sensing means; a cut-off valve and a fixed orifice in one of said ports to permit air to pass therethrough from the atmosphere to said air path means when the engine temperature reaches the final temperature during the warming-up phase of the engine; a variable orifice valve in the other port to permit additional air to pass therethrough from the atmosphere to said air path means in proportion to increasing engine temperature over the operating temperature range, said operating temperature range being higher than the final temperature of the warming-up phase of the engine, whereby the density of the gas mixture is maintained at a substantially high level over lower temperature range compared to the final temperature of the warming-up phase, said density being held at a substantially low level over higher temperature compared to the final temperature of the warming-up phase.
 2. The air bleed adjusting device as defined in claim 1 wherein the amount of bled air is relatively increased at a rapid rate upon reaching the final temperature of the warming-up phase and then increased less rapidly in proportion to increase in temperature of the engine. 